One really handy way to begin learning about the tank due to specific details you've mentioned is to do a full water change, all of it. Match temp and salinity to the old water no other params matter. This is the rationale:
Any rebound of those numbers means a protein source is hidden in the rocks, unlikely but possible once you discover if they used be live rocks and then were dried out with all the animals still inside (a source for organic waste in the rock which when sitting in water a month can release ammonia due to tissue decay)
It's already been submerged a month, a full wc isn't going to undo anything, it's a gauge for organic loading. If your numbers don't rebound to that above, and you still don't add anything to the tank, that tells us no ammonia stores are in the tank. My thread linked shows what to add to begin the ammonia process again if needed
To me it's just as interesting for you to reset the numbers yourself with a full complete water change and see if they rebound as it is to post the initial reading. A full water change cannot hurt your tank I've done hundreds in my fully stocked tank